In contrast to wireless communication systems of the related art providing only voice-oriented services, advanced wireless communication systems, such as high speed packet access (HSPA), long term evolution (LTE) or evolved universal terrestrial radio access (E-UTRA) and LTE-advanced (LTE-A or E-UTRA evolution) of 3rd generation partnership project (3GPP), high rate packet data (HRPD) and ultra mobile broadband (UMB) of 3GPP2, and institute of electrical and electronics engineers (IEEE) 802.16e, may provide high-speed and high-quality packet data services. The LTE-A system as an evolved version of the LTE system supports carrier aggregation (CA), higher order multiple input multiple output (higher order MIMO), and other technologies in addition to existing LTE functionalities. In the description, LTE-A and LTE may be used interchangeably.
In the LTE or LTE-A system as a representative example of wideband wireless communication systems, orthogonal frequency division multiplexing (OFDM) is employed for the downlink and single carrier frequency division multiple access (SC-FDMA) is employed for the uplink. Such multiple access schemes may separate individual pieces of user data or control information by allocating or maintaining time-frequency resources to carry user data or control information so that they do not overlap with each other (i.e., so that orthogonality is preserved).
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.